Board 28, West deals, NS vulnerable.
♠ 973
♥ 109
♦ KQ10973
♣ Q4
♥ 109
♦ KQ10973
♣ Q4
♠ J108
♥ 753
♦ 32
♣ K8652
♥ 753
♦ 32
♣ K8652
♠ KQ52
♥ 86
♦ 85
♣ J10973
♥ 86
♦ 85
♣ J10973
♠ A64
♥ AKQJ42
♦ AJ6
♣ A
♥ AKQJ42
♦ AJ6
♣ A
With West passing, some Norths opened with a diamond preempt and South can Blackwood into the grand slam.
However playing some sort of Multi 2♦ North can't bid a weak 2♦ and probably won't bid 3♦ when red vs. white. In that case South gets to open with 2♣.
Then it may go 2♦ by North showing 0-7 HCP, 2♥ by South and 3♦ by North. South is then at a crossroads. I think a rebid of 3♥ is short-sighted because the only thing that matters at this point is the quality of North's diamonds. 4NT as key card Blackwood seems the only rational call without other sophisticated methods.
Playing 0314 responses North will bid 5♦ and South can bid 5♥ to ask for the diamond Queen and reach 7NT... unless partner decides that's a signoff... clearly there are many ways to screw this up!
How would you and your partner bid this?